Suction bend conduit for use with centrifugal pumps

ABSTRACT

A tubular curved conduit body is provided with an inlet and an outlet, the latter to be connected with the intake of a centrifugal pump. One or more guide vanes extend across the passage of the conduit intermediate the inlet and outlet and are each composed of two sections fast with the conduit body at diametrally opposite locations and having inner ends which extend toward but are spaced from one another.

United States Patent [191 Holzhuter June 28, 197

[ 1 SUCTION BEND CONDUIT FOR USE WITH CENTRIFUGAL PUMPS [75] Inventor:Erich Holzhuter,

Lutzelsachsen/Weinheim, Germany [73] Assignee: Klein, Schanzlin, BeckerAktiengesellschaft, Frankenthal (Pfalz), Germany 221 Filed: July 13,1972 21 Appl.No.:272,91l

[30] Foreign Application Priority Data July 14, 1971 Germany 2135097[52] US. Cl 138/39, 415/183, 415/216, 415/208 [51] Int. Cl..- Fl5d U114[58] Field of Search 415/183, 185, 184, 208, 415/209, 219; 138/37, 39

[56] References Cited UNITED STATES PATENTS 1,532,118 4/1925 Bayles415/183 2,112,608

3/1938 Schmidt 415/183 2,306,742 12/1942 Moody 415/183 2,640,470 6/1953Haltenberger..... 138/39 3,425,189 2/1969 Haselmayern. 138/37 3,494,3792/1970 Hinden 138/39 FORElGN PATENTS OR APPLlCATlQNS 387,935 1/1924Germany 138/39 1,228,223 4/1971 Great Britain 138/39 1,267,149 6/1961France 415/208 1,019,045 11/1957 Germany 1,049,367 10/1953 France415/208 Primary Examiner-Henry F. Raduazo Attorney, Agent, orFirm-Michael S. Striker [57,] ABSTRACT A tubular curved conduit body isprovided with an inlet and an outlet, the latter to be connected withthe intake of a centrifugal pump. One or more guide vanes extendacross'the passage of the conduit intermediate the inlet and outlet andare each composed of two sections fast with the conduit body atdiametrally opposite locations and having inner ends which extend towardbut are spaced from one another.

2 Claims, 4 Drawing Figures SUCTION BEND CONDUIT FOR USE WITHCENTRIFUGAL PUMPS BACKGROUND OF THE INVENTION The present inventionrelates to conduits, and in particular to suction bend conduits for usewith centrifugal pumps. Still more particularly the invention relates toa suction bend conduit for use with centrifugal pumps having a highsystem pressure.

Suction bend conduits for use with centrifugal pumps are known per se.Their purpose is to be connected with the intake of the pump, so thatthe fluid for the pump is supplied through the suction bend conduit. Theparticular reason for the provision of such suction bend conduits is toreduce the flow losses and/or to equalize the flow speed profile of thefluid as it issues from the suction bend conduit into the pump. For thispurpose the suction bend conduits according to the prior art areprovided with guide vanes which deflect the fluid and cause it to changeits direction during the movement of the fluid through the suction bendconduit. Particularly where centrifugal pumps with high speed operationare used, where for structural reasons a suction bend conduit ofidentical inlet and outlet cross section must be arranged immediatelyupstream of the pump intake, it is necessary to provide guide vanes inthe suction bend conduit in order to avoid damage to the pump resultingfrom vibrations and also to avoid lossesin'the operationaleffectiveness. Here, again, the guide vanes equalize the full speedprofile of the fluid as it issues from the suction bend conduit into theintake of the pump.

However, while these guide vanes thus are advantageous in certainapplications, there are also situations where they can bedisadvantageous. In particular, these guide vanes have drawbacks if theyare used in suction bendconduits which are under high internal pressureand if the guide vanes are either arranged in form of a grid ofintersecting guide vanes or under some circumstances even if the guidevanes all extend in one and the same direction across the passage of thesuction bend conduit. The reason for this is that there develops theso-called tie rodeffect which causes locally high crest peaks in thewall of the suction bend conduit. In addition to-this difficulties exist-by comparison with the manufacture of a suction bend conduit withoutguide vanesin making suction bend conduits which are provided with suchguide vanes because the guide vanes can be inserted and welded to thesuction bend conduit only after the two sections of which such suc tionbend conduits are usually made, have already been welded together.

Yet, suction bend conduits with guide vanes are of importance, forinstance they are used in the main cooling fluid conduits for the pumpsin atomic reactors where the safety requirements are particularly high.To meet these safety requirements which are intended to assure againstdamage or malfunctioning of the pumps, the use of suction bend conduitsprovided with guide vanes is essential because the cross-section of thepump intake and that of the fluid supply conduit must for safety reasonsbe no greater than the cross section of the suction bend conduit outlet,and because furtherthe amount of cooling fluid (usually water) which ispresent in the conduits.

SUMMARY OF THE INVENTION It is a general object of the present inventionto overcome the disadvantages of the prior art.

More particularly it is an object of the present invention to provide animproved suction bend conduit of the type here under discussion, whichis provided with one or more guide vanes but avoids the disadvantages ofthe prior art.

In pursuance of these objects, and of others which will become apparenthereafter, one feature of the invention resides in a suction bendconduit for use with centrifugal pumps, comprising a tubular curvedconduit body having an interior passage provided with an inlet and withan outlet which is adapted to be connected with the intake of acentrifugal pump. At least one guide vane is also provided, extendingacross the passage intermediate the inlet and the outlet and beingcomposed of two sections having respective outer end portions fast withthe conduit body and inner end portions which are spaced from oneanother in direction transversely of the passage.

In other words, the guide vane or vanes are not of one piece but of two,being transversely subdivided. This measure assures that the tie rodeffect is eliminated. Moreover, the manufacture of this suction bendconduit can now be effected in the same manner in which suction bendconduits without guide-vanes are produced, because each guide vanesection can be welded into a respective suction bend conduit half beforethe two halvesofthe conduit are welded together.

It is further possible not only to provide a single guide vane, but aplurality of guide vanes which are spaced from one another in thelongitudinal direction of the passage of the suction bend conduit,whereby additional'advantages can be obtained. In particular, thethickness of the guide vanes can be determined by appropriate profileconfiguration of the guide vanes, in accordance with considerations ofvibratory problems without having to accept hydrodynamic disadvantages.By contrast, the known grid-shaped arrangement of the guide vanes limitsthe thickness of the guide vanes due to hydrodynamic considerationsresulting from the construction effect of grid-shaped arrangements.

The novel features which are considered as characteristic for theinvention are set forth in particular in more the suction bend conduitmust be located immediately upstream of the pump to reduce to a minimumthe appended claims. The invention itself, however, both as to itsconstruction and its method of operation, together with additionalobjects and advantages thereof, will be best understood from thefollowing description of specific embodiments when read in connectionwith the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic plan view,partly shown in phantom lines, illustrating an embodiment of theinvention;

FIG. 2 is a section taken on line A-B of FIG. 1;

FIG. 3 is a diagrammatic axial section through a further embodiment ofthe invention; and

FIG. 4 is an end view of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly theembodiment in FIGS. 1 and 2 it will be seen that here a suction bendconduit is illustrated having an inlet portion 1 and an outlet portion3. In other words, the inlet portion 1 would'be connected with asuitable supply of fluid and the outlet portion 3 would be connectedwith the intake of a centrifugal pump. Located in the suction bendconduit 1, 3 are transversely extending guide vanes 2 which are curvedin the direction of fluid flow in order to impart an appropriate flow tothe fluid. In accordance with the invention, and as shown particularlyin FIG. 2, each of the transversely extending guide vanes 2 is composedof two guide vane sections 2 one of which is secured by welding orotherwise to the wall of the suction bend conduit at one side and theother of which is secured to the same wall at the diametrally oppositeside. The sections 2 have inner free ends which are located adjacent oneanother but are spaced. In other words, and as shown in FIG. 2, the freeends of the sections 2' are not connected but define with one another agap.

A further embodiment is illustrated in FIGS. 3 and 4 where the suctionbend conduit is shown as having a plurality of transversely extendingguide vanes 2a, 2b and 20. Of course, the number may vary but it will benoticed that here again they extend transversely of the interior of thesuction bend conduit intermediate the inlet end 1 and the outlet end 3,being spaced longitudinally of one another along the elongation of thesuction bend conduit. In accordance with the invention, and as shown inFIG. 4, each of the guide vanes (only the guide vane 2a is shown in FIG.4) is composed of two guide vane sections 2'a which again define withtheir inner free ends a gap, meaning that these inner free ends are notconnected with one another.

It will be appreciated that only a single guide vane 2 or 2a could beprovided, for instance in the embodiment of a normally configurated andparticularly advantageous suction bend conduit as shown in FIGS. 3 and4, but that the number of guide vanes may be selected in accordance withthe requirements of a given application.

In resorting to the present invention it is particularly advantageousthat the curved configuration of suction bend conduits without guidevanes, can be employed in suction bend conduits provided with guidevanes according to the present invention. It is well known that inconventional suction bend conduits having guide vanes a sufficient fluiddeflecting effect can be obtained with low flow losses only if -giventhe configuration of the guide vanes in grid-shaped mannerthe suctionbend conduit is composed of three sections, namely an inlet section, anoutlet section extending at right angles to the inlet section and anintermediate section which is welded together with the inlet and outletsections and interposed between them. The grid of guide vanes is weldedinto the intermediate section. The difficulty with this prior artarrangement is that there are disadvantages involved in such aconstruction, particularly with respect to the structural strength whichcan be obtained, because a substantial stress concentration develops inthe intersecting lines of the respective conduit sections. This-isavoided with the construction according to the present invention, as isclearly evident from FIGS. 3 and 4.

A further advantage according to the present invention is the fact thatif the suction bend conduit has a relatively substantial internaldiameter, and'is interposed in a conduit sufficiently large to permitentry of a human operator, the invention makes it possible for theoperator to enter and pass through the suction bend conduit itself aslong as the suction bend conduit has an internal diameter ofapproximately 800 mm or more.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other thpes ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in asuction bend conduit for use with centrifugal pumps, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A suction bend conduit for use with pumps, particularly centrifugalpumps, comprising a tubular conduit body having an interior passage,said conduit body including an inlet part for the admission of a fluidflowing in a first direction, an outlet part for the discharge of saidfluid in a different second direction, and an intermediate part forchanging the direction of flow of said fluid from said first directionto said second direction, said outlet part being adapted to be connectedwith the intake of a pump; and at least one row of guide vanes extendingacross said passage in said intermediate part and each vane beingarcuate in a sense between said first and second direction so as to aidin changing the direction of flow of said fluid, each guide vane in saidrow of guide vanescomprising two separate sections having respectiveouter end portions fast with said conduit body and inner end portionswhich are spaced from one another in a direction transversely of saidpassage so as to define a gap, and said sections having a combinedlength in transverse direction of said passage which exceeds the widthof said gap.

2. A suction bend conduit as defined in claim 1; wherein said conduitbeing an arcuate bend between said first and said second direction, andsaid row of vanes being positional along said bend between said firstand said second direction.

1. A suction bend conduit for use with pumps, particularly centrifugalpumps, comprising a tubular conduit body having an interior passage,said conduit body including an inlet part for the admission of a fluidflowing in a first direction, an outlet part for the discharge of saidfluid in a different second direction, and an intermediate part forchanging the direction of flow of said fluid from said first directionto said second direction, said outlet part being adapted to be connectedwith the intake of a pump; and at least one row of guide vanes extendingacross said passage in said intermediate part and each vane beingarcuate in a sense between said first and second direction so as to aidin changing the direction of flow of said fluid, each guide vane in saidrow of guide vanes comprising two separate sections having respectiveouter end portions fast with said conduit body and inner end portionswhich are spaced from one another in a direction transversely of saidpassage so as to define a gap, and said sections having a combinedlength in transverse direction of said passage which exceeds the widthof said gap.
 2. A suction bend conduit as defined in claim 1; whereinsaid conduit being an arcuate bend between said first and said seconddirection, and said row of vanes being positional along said bendbetween said first and said second direction.